1. Field of the Invention
The present invention relates to wireless selective calling systems, and in particular to a message transceiver such as a selective call receiver with transmission function and a message transmission control method therefor.
2. Description of the Related Art
Recently, there has been proposed a selective call receiver with a message transmission function, for instance, in Japanese Patent Laid-open Publication No. 6-209276. This kind of receiver is provided with a DTMF (Dual Tone Multi-frequency) transmitter and memories storing conversion tables such as a character matrix table and a fixed-message table. In the case where a user creates a desired message (hereinafter, called "free word message"), the character matrix table is searched for the corresponding codes depending on the user's instructions. The created message is transmitted by the DTMF transmitter through the telephone network and then the selective calling system to the destination selective call receiver. In Japan, since the character matrix table for free word message has been standardized, a free word message can be transmitted through any common carrier.
In such a selective calling system, however, it is difficult to increase a length of transmission message because a longer message occupies a line for a longer time, resulting in a network traffic jam. Especially, in the cases where the caller's name is transmitted so that the called party can know who is calling, the number of free word message characters becomes smaller. Therefore, there are available some selective call receivers where input characters are canceled and cleared when exceeding a predetermined limit. The user of such a receiver needs to create a message while looking at the number of message characters.
Further, at present, the number of message characters available is different from one common carrier to another. Therefore, the user further needs to know which common carrier provides the selective call receiver of the opposite party before creating a message while looking at the number of message characters which is determined in the common carrier of the destination receiver.